Meeting

The neotectono-sedimentary processes of the South China Sea abyssal basin have long been a puzzling issue and are still debated because of the lack of drilling evidence. In this study, we interpreted four multi-channel seismic profiles across the Southwest Sub-basin (SWSB), integrated for stratigraphic correlation with new drilling data from the Integrated Ocean Discovery Program （IODP） 349 Expedition. Results show that the Neogene sediments are divided into four stratigraphic units, each with distinctive seismic reflectors.

We investigate the characteristics of turbulent flows within near-bottom hydrothermal plumes at mid-ocean ridges through quantitative analysis of video images from manned submersibles using the Particle Image Velocimetry (PIV) method. High-quality video images of near-bottom hydrothermal vents were selected from the Data Library and Archives of the Woods Hole Oceanographic Institution (WHOI), consisting of multiple examples of vent fields in the Atlantic, Pacific, and Indian Oceans.

Marine magnetic lineation is an important media to interpret the age and spreading process of the oceanic crust. But there are many difficulties to identify the lineation from sea surface observation in a deep and narrow inactive ocean basin located in the low-latitude. Located in such a tectonic position, the spreading history of the Southwest subbasin of the South China Sea became a long time controversy. the deeptow data were able to increase observed anomaly amplitudes by a factor of ~4.

Oceanic crust undergoes rapid transformation in both its thermal and physical structure within the first 10 Ma from the ridge axis. Large departures in observed heat flow measurements from global depth and heat flow models reveal the importance of hydrothermal systems in heat dissipation and crustal alteration. Hydrothermal systems have the greatest influence on young oceanic crust due to its high porosity and permeability and low sediment cover. Much is still unknown about the scale and processes involved, especially the interaction between the solid Earth and the oceans.

We investigate the relationship among hotspot influence, local magma supply, and asymmetric topography and crustal structure of the conjugate flanks of the slow-spreading Mohns Ridge. Residual mantle Bouguer anomaly (RMBA) was calculated by subtracting from free-air gravity the predicted attractions of water-sediment, sediment-crust, and crust-mantle interfaces as well as the effects of lithospheric cooling.

The NERC-funded joint geophysical and oceanographic OSCAR project aims to develop understanding of the interactions between relatively young oceanic crust and the overlying abyssal ocean through heat transfer and fluid flow. The movement of hydrothermal fluids through the oceanic crust causes changes in its structure and composition: circulating heat, precipitating minerals in open cracks and fractures, and forming alteration fronts which influence permeability and seismic properties, though little is known about the rate and extent of these processes.

The InterRidge cruise bursary is aimed at post graduate students seeking cruise experience. This provides a vital opportunity for training in data collection and experience of scientific principles in action. The bursary allowed me to join Dr. R. Hobbs’ JC114 cruise to the Panama basin to study the Costa Rica and Ecuador ridges. Subsequently after the cruise I became involved in the OSCAR project, ‘Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge’.

Abyssal peridotites are of great interest to geoscientists because they provide direct information about the present-day Earth's mantle. Os isotope systems in abyssal peridotites are also interesting because Os is a highly siderophile and compatible element and so concentrates in the core in preference to the mantle, and in the mantle in preference to the crustal materials. In addition, Os in abyssal peridotites is not susceptible to metasomatism and alteration by sea water.

We quantify systematic variations in morphological characteristics of global transform faults and investigate their dependence on spreading rate, local magma supply, and other tectonic variables. Detailed analyses were conducted on 78 transform faults where high-resolution multibeam bathymetry and other geophysical data are available.